I think there is a massive issue concerning cloning in terms of "playing God" as other people above has suggested. I think one of the massive strengths of our species is the fact that we are all different and therefore have different gifts and abilities. In a sense, although various cultures prize some gifts and abilities above others, we need to realise that we need everybody and everybody has a part to play. Having one type of human cloned is therefore rather a worry.

Leaving the "Playing God", "embryos feeling pain", "harvesting stem cells being tantamount to murder," and the alike aside, let us look at basic reason why organisms have sexual reproduction. Sexual reproduction involves the random combination of genes from two different organisms that leads to different characteristics in the offspring, part of which are from one parent and the rest from the other. If this mixture of characteristics makes it easier for the offspring to survive, it does and carries forward the gene pool it has acquired to be passed on to future generations. If the gene pool of the offspring does not favor its survival over the others it dies and does not pass on its gene pool. This is how humans have evolved to reach the stage they are at.

Though the huge advancements in medical science have made it possible for humans with a less optimal gene pool to survive, there is certainly evolution taking place at some level. Cloning stops the process of evolution completely.

This makes me feel that cloning is not something that all humans should adopt and have offspring with the same genetic characteristics as themselves. Even if it is possible to clone it should be done only where there is a valid reason for doing so.

Those who are uncomfortable with cloning need not derive any benefits from the science of cloning.

As #6 states, new techniques have eliminated the need to harvest cells from embryos; what are people's opinions now that that issue is completely out of the way?

Since several years ago Dolly the Sheep was completely cloned, I can't imagine the day isn't at hand (if it's not been at hand already) that humans will be cloned. This is an interesting dilemma -- do clones have the same Rights as the "Original?"

I, too, feel very conflicted with cloning. While I know that cloning may have a very positive impact on the medical world, I have a hard time giving my "okay" on the killing of an embryo. That being said, I do not know how I would feel if I had a child whose life could be dramatically different with the cells from a cloned embryo.

Cloning no longer needs to use embryonic stem cells. With modern techniques, either adult stem cells can be used, or new stem cells can be grown from other cells. It all comes down to actually researching the facts. Besides, an ethical objection to use of embryonic stem cells in research is not actually focused on the research, the stem cells, or even the ethics of duplicating a human genomic structure; all objections in that vein are actually anti-abortion in nature, and are clouding the issue. Since abortion is a legal procedure in America, there should be no restrictions on how to dispose of the fetal tissue after the operation; I would rather a legally aborted fetus be used in research that could save lives than be thrown out to make anti-abortionists happy. (Not getting into abortion itself; that's another discussion.) Right now, the focus should be entirely on the human being itself and what makes it human -- a soul? Sentience? Self-awareness or abstract thought? Besides, until we can actually clone an entire, healthy human, the issue is moot. Research is research and should not be limited when there is no legal -- or, in my mind, ethical -- reason to do so.

The previous answers are all excellent and thoughtful. Here's a pragmatic test-case. Imagine that a baby is born to the Smiths and that this baby has severe and extremely painful birth defects. Imagine next that the Smiths could create a new embryo from which stem cells could be harvested and that these cells would certainly repair the extremely painful, life-long problems from which their infant suffers. Would the Smiths be justified, in that case, in taking cells from an embryo that would not suffer in order to radically improve the life of a child already suffering severely? I don't pretend that answering this question will be easy.

I personally, as a Christian, do not feel comfortable with reproductive cloning. It smacks of playing God, which humans don't have the wisdom to do even if we had the ability.

I am praying that some day a method will be developed to allow for obtaining stem cells without the destruction of an embryo - from the placenta or umbilical cord after the birth, or from fetuses that have been miscarried, perhaps? It sounds like there could be significant medical possibilities for treatments if the stem cells could be obtained in an ethical manner.

I think that one's attitude towards this depends completely on one's beliefs about when life begins. If life begins at conception, then there is a huge problem with therapeutic cloning. It becomes tantamount to harvesting body parts from living people. If live doesn't begin at conception, no problem. So it's a debate that can never be won or lost because it depends completely on your (unarguable) attitude about when life begins.

Well, it depends who you ask; there are basically two opposing viewpoints on the subject of cloning, and those are obviously "for" and "against". The Catholic church and a substantial number of other religious institutions recognize life begins with conception, when a human egg is fertilized by a human sperm. If allowed to develop to term, the result will be another human life. Judaism does not recognize life beginning at conception, although there is some concern and many question the wisdom of cloning.

Interestingly, therepeutic cloning doesn't sound so bad, until one realizes it requires the harvesting of stem cells (cells that are not differentiated yet) from unborn embryos, resulting in the embryo's death. When it is viewed in that light, it will have the same acceptance as experimental cloning does with the majority of religious institutions, that "no experimental process should be conducted upon any living person that would result in harm or death to that person".

My own personal opinion is we can push the "help wagon" too far. Many of these experiments are done in an effort to expand the body of scientific knowledge we already possess. Without the experimentation that has led us up to this point, we wouldn't have the progress we have attained in certain areas thus far. I think cloning, however, might be pushing past the limits of what God Almighty has established as optimum operating conditions; if we do proceed, it should be with the utmost caution.